pinctrl: renesas: rzg2l: Remove RZG2L_TINT_IRQ_START_INDEX

pinctrl: renesas: rzg2l: Remove RZG2L_TINT_IRQ_START_INDEX

The RZ/V2H(P) SoC has 16 IRQ interrupts, while every other SoC has 8,
and this affects the start index of TINT interrupts (1 + 16 = 17, rather
than 1 + 8 = 9).
Macro RZG2L_TINT_IRQ_START_INDEX cannot work anymore, replace it with a
new member within struct rzg2l_hwcfg.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://lore.kernel.org/20240930145244.356565-2-fabrizio.castro.jz@renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>